Japanese Unexamined patent publications 2000-41392, 2003-174790, and 2006-33897 disclose motor systems with motors each of which is equipped with first and second sets of three-phase windings. Note that these Japanese Unexamined patent publications 2000-41392, 2003-174790, and 2006-33897 will be respectively referred to as first, second, and third publications, hereinafter.
Each of the motor systems also includes first and second inverters individually energize the respective first and second sets of three-phase windings.
The first and second publications, whose applicant is the same as this application, also disclose a configuration of first and second sets of three-phase windings in which the first set of three-phase windings is spatially shifted from the second set thereof by an electric angle of π/6 or π/3 radian in phase.
In the first and second publications, even if a fault occurs in one phase winding in, for example, the first set of three-phase windings, the second inverter can normally energize the second set of three-phase windings, thereby continuously operating the motor-generator even in the event of one-phase winding failure.
In such motor systems whose first and second sets of three-phase windings are configured to be individually driven by corresponding first and second inverters, how to specifically energize the first and second sets of three-phase windings may have not been sufficiently disclosed. For this reason, users have been awaited suggestions about how to specifically energize the first and second sets of three-phase windings.